Chloridotris(pentafluorobenzenethiolato-κS)[tris(4-fluorophenyl)phosphine-κP]osmium(IV)

The title complex, [Os(C6F5S)3Cl(C18H12F3P)], displays a trigonal-bipyramidal OsIV coordination geometry with the S atoms of three thiolate ligands occupying the equatorial positions. The thiolate pentafluorophenyl substituents are all placed above the equatorial plane, forming a claw-like cavity which accommodates the chloride ligand with a normal Os—Cl bond length. The phosphine ligand trans to the chloride ligand reveals a short Os—P bond length compared to other chloride–phosphine OsIV complexes (average = 2.40 Å). This strong bonding indicates that the inductive effect of the F atoms in the phosphine does not affect significantly its basicity, compared to triphenylphosphine. This feature is also consistent with the known poor trans influence of Cl−. The crystal packing involves π–π contacts between inversion-related thiolate C6F5 rings, with a centroid–centroid separation of 3.659 (8) Å.

The title complex, [Os(C 6 F 5 S) 3 Cl(C 18 H 12 F 3 P)], displays a trigonal-bipyramidal Os IV coordination geometry with the S atoms of three thiolate ligands occupying the equatorial positions. The thiolate pentafluorophenyl substituents are all placed above the equatorial plane, forming a claw-like cavity which accommodates the chloride ligand with a normal Os-Cl bond length. The phosphine ligand trans to the chloride ligand reveals a short Os-P bond length compared to other chloride-phosphine Os IV complexes (average = 2.40 Å ). This strong bonding indicates that the inductive effect of the F atoms in the phosphine does not affect significantly its basicity, compared to triphenylphosphine. This feature is also consistent with the known poor trans influence of Cl À . The crystal packing involvescontacts between inversion-related thiolate C 6 F 5 rings, with a centroid-centroid separation of 3.659 (8) Å .
geometry (e.g. Mendoza et al., 2006;Cerón et al., 2006;Arroyo et al., 2009), with the phosphine and one thiolate groups placed in axial positions. Of interest are the complexes [OsX(thiolate) 3 (phosphine)], where X is an halogen trans to the phosphine in a bipyramidal geometry (Hills et al., 1991;Arroyo et al., 1994)and halides are known to have little trans influence, allowing the estimation of the basicity of the coordinated phosphine.
The title complex was obtained by reaction of [Os(SC 6 F 5 ) 4 (P(C 6 H 4 F-4) 3 )] (space group P1, Arroyo et al., 2009) and HCl(aq) in acetone (see Experimental). The complex approximates 3-fold symmetry (Fig. 1), with atoms P1 and Cl1 placed in axial positions. The coordinated Clion is placed in a cavity approximating point symmetry C 3 , formed by the C 6 F 5 groups of the thiolate ligands, all 'up' towards and around the smaller chloride ligand. The trigonal-bipyramidal coordination geometry of the Os IV centre is completed by three S atoms in the equatorial plane.
The chloride ligand is found at the expected distance from the metal center, Os-Cl = 2.414 (2) Å, which compares well with the average Os-Cl bond length retrieved from 804 hits in the CSD, 2.401 Å (CSD, version 5.31 with all updates; Bruno et al., 2002). A quite different situation is observed for the phosphine: the Os-P bond is short, 2.334 (2) Å, compared to other Os IV complexes including the P-Os-Cl fragment (ca. 2.40 Å). For all the 340 hits retrieved in the CSD with a P-Os-Cl fragment, the average Os-P bond length is 2.383 (2) Å. The phosphine is thus strongly bonded to the metal centre in the title compound. In spite of the inductive effect of the F atoms in the phosphine, a significant amount of electron density should be donated back to the rings and the P atom, favoring the ligand bonding. This behaviour is consistent with the pK a of that phosphine, 1.97, which is close to the pK a of triphenylphosphine, 2.73 (Allman & Goel, 1982). Finally, the strong coordination of tris(4-fluorophenyl)phosphine in the title compound also affects the geometry of this ligand: short P-C bond lengths are observed, in the range 1.787 (10)-1.797 (10) Å, while the mean P-C distance reported in the free tris(4-fluorophenyl)phosphine is 1.825 (5) Å (bin Shawkataly et al., 1996).
The crystal structure is stabilized by intermolecular π-π interactions involving C 6 F 5 rings of thiolate ligands related by an inversion centre (Fig. 2). The separation between the centroids of stacked rings is 3.659 (8) Å.

Refinement
Diffraction data were collected at room temperature, and completeness was reduced to 0.99 because 68 reflections were rejected during data reduction. As commonly found in perfluorinated complexes, F atoms display high displacement parameters. As a consequence, significant Hirshfeld differences are observed for some C-C and C-F bonds in the thiolate groups. Limited accuracy is also reflected in the small C-C average bond length in benzene ring C31···C36 (ca. 1.36 Å).